Corrugated container having access door

ABSTRACT

A fiberboard container is constructed from an outer blank of corrugated fiberboard and a separate and distinct inner liner of corrugated fiberboard which is laminated interior thereof. A generally rectangular access door is located in one of the sidewall panels with its upper edge colinear with the upper edge of the panel. The door is hinged to the remainder of the outer blank along another edge. The access opening through the inner liner is smaller than the access door and provides a positive stop at both remaining edges of the door.

United States Patent 119 1111 3,891,137

Ellison et a]. 1 June 24, 1975 [54] CORRUGATED CONTAINER HAVING 2,797,039 6/1957 Belsinger 229/44 R X D00 2,974,779 3/1961 Belsinger 229/43 X ACCESS R 3,099,379 7/1963 Stease 229/23 R [75] Inventors: Donald E. Ellison, Clayton; Larry C. 3,262,631 7/ I966 Belsinger 229/44 R X Davenport, Indianapolis, both of Primary Examiner-George F. Mautz [73] Assignee: Inland Container Corporation, Attorney, 8 0F Even. Tabin &

Indianapolis, Ind. eka

[22] Filed: May 11, I973 [21] Appl. No.: 359,345

[5 7 ABSTRACT A fiberboard container is constructed from an outer blank of corrugated fiberboard and a separate and disl Cl 229/44 229/23 7 R tinct inner liner of corrugated fiberboard which is lam- [5 [1 Int. Cl 865d 5/66 i ted interior thereof. A generally rectangular access Field of Search 229/44 37 51 door is located in one of the sidewall panels with its 229/39 43 206/278, 282 upper edge colinear with the upper edge of the panel.

The door is hinged to the remainder of the outer blank [56] Refere ces C t along another edge. The access opening through the UNITED STATES PATENTS inner liner is smaller than the access door and pro- 264,383 9/1882 Weiner 229/44 R vides a Positive stop at both remaining 'gdges of the 2,301,310 11/1942 Messer.... 229 44 R x 2,465,842 3/1949 Brooks 229 44 R x 2,648,480 8/1953 Belsinger........,.............. 229 23 R x 5 4 Drawmg CORRUGATED CONTAINER HAVING ACCESS DOOR This invention relates to corrugated fiberboard bulk containers with access doors for manual loading and/or unloading and having sufficient structural strength to contain heavy loads.

Large corrugated containers have become more and more frequently used for shipment of bulk products. To aid in the manual loading or unloading of such large containers, particularly with products such as melons and the like, access doors may be provided in one or more panels.

Because of the heavy weights of products sometimes shipped, the vertical panels of bulk containers are often reinforced with an inner liner to provide stacking strength, bulge resistance, and overall product protection in distribution. The provision of access doors in conventional reinforced bulk containers has substantially weakened container strength, thereby requiring additional material, or the use of higher strength and more expensive materials, to overcome such weakness created by access doors. It has also been difficult to adequately secure the access door in closed position.

Accordingly, an object of this invention is to provide a reinforced bulk container with an access door that does not substantially weaken the container.

Another object of this invention is to provide a reinforced bulk container with an access door, which container can be manufactured inexpensively.

A further object of this invention is to provide a bulk container having an access door which may be securely and easily fastened in the closed position.

These and other objects of the invention are more particularly set forth in the following description and in the accompanying drawings of which:

FIG. 1 is a perspective view of a bulk container having various features of the invention, showing its access door in the open position;

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a perspective view showing the interior of an alternative container having various features of the invention; and

FIG. 4 is a sectional view taken along line 44 of FIG. 3.

The invention generally provides a reinforced bulk container having an access door wherein the inner liner provides lateral stops at each side of the access door while also providing reinforcement at all four corners of the container to assure adequate stacking strength. The fabricated bulk container is formed from two blanks, usually made of singlewall or doublewall corrugated fiberboard, and for purposes of clarity, the inner blank is referred to as a liner although it should be understood that it may include upper and/or lower closure flaps or the like.

FIGS. 1 and 2 illustrate a bulk container fabricated from an outer blank I and an inner liner, both of which are divided into four sidewall panels 3, 4, 5 and 6 by parallel vertical score lines 7, 8, 9, and 10, with prime numbers being used to identify the components of the inner liner 2. Hinged to the upper edges of the sidewall panels 3, 4, 5 and 6 are top closure flaps ll, l2, l3 and 14. Similarly hinged to the bottom edges of the sidewalls are bottom closure flaps 15, l6, l7 and 18. The top and bottom closures may vary, depending on the LII preference of the users of the containers; for example, some may have flanges rather than closure flaps or may employ a separate tray-type closure. The inner liner 2 has substantially the same depth as the outer liner 1 and is laminated to the major portion of the inner surface area of the vertical sidewall panels 3, 4, 5 and 6. The illustrated inner liner 2 does not have closure flaps, but such flaps could be provided. In many instances, it will be desirable to provide bottom closure flaps to reinforce those on the outer blank.

A pair of parallel vertical cuts are provided in the sidewall panel 4 of the outer blank extending parallel to score lines 7 and 8 downward from the upper edge of closure flap l2, and these cuts create an access door 20. The distance between vertical cuts may vary, up to an amount equal to the width of sidewall panel 4; however, the cuts are preferably positioned at least two inches from the corners defined by score lines 7 and 8 so as not to detract from the stacking strength. The cuts are also preferably positioned so that each lies an equivalent distance from the vertical centerline of sidewall panel 4 so the access door 20 is centrally located.

Two parallel vertical cuts are also provided in the panel 4 of the inner liner 2, which panel is laminated to the sidewall panel 4, these cuts being spaced closer together than those in the outer blank and thus creating an access opening 22 which is narrower than the access door 20. The cuts are similarly positioned so that each is an equivalent distance from the vertical centerline of panel 4 so the access opening 22 is centered therein.

A pair of horizontal lines of weakness 24 are provided in the outer blank 1, extending between the vertical cuts near the lower ends thereof, and it is along these lines of weakness 24 that the access door 20 is hinged to the remainder of the outer blank. Similar horizontal lines of weakness, which may be score lines, partial slits or the like, are provided in the inner liner 2 at the corresponding location. Although the plug portion 25 of the inner liner 2 lying between the vertical cuts could be removed from the inner liner prior to lamination, it is preferably allowed to remain and is laminated to the interior surface of the access door 20. The purpose of the double lines of weakness 24 is to facilitate folding the door 20 downward to a position where it lies adjacent the exterior surface of the remainder of the panel 4. By dimensioning the depth of the access door 20 to be about one-half the depth of the container, the access door 20 can be easily held in the open position by tucking the flap 12 under the container,

Because the access opening 22 in the inner liner is narrower than the access door 20, a pair of lateral stops 26 for the access door 20 are provided by those portions of the inner liner 2 immediately flanking the access opening 22. The provision of such a pair of lateral stops 26 support both side edges of the access door 20, thus preventing it from being pushed inward beyond the vertical position and possibly damaging the merchandise disposed in the container. Moreover, these stops 26 provide means for conveniently securing the access door 20 in its closed position. Admittedly, the access door 20 is usually the weakest region in a bulk container of this type, and in some instances the additional strength in the door conveniently provided by the laminated plug 24 may be advantageous.

The alternative embodiment, illustrated in FIGS. 3 and 4, provides a reinforced bulk container fabricated from a generally similar outer blank 30 which is divided into pairs of vertical sidewall panels 32 and 34 by verti cal score lines. The outer blank 30 has similar top closure flaps 36 and 38 and bottom closure flaps 40 and 42. A glue flap 44 or the like is provided for the formation of a manufacturers joint.

Vertical cuts and a horizontal score line 46 define an access door 48 in the outer blank 30. The parallel vertical cuts extend downward from the upper edge of the closure flap 38, each cut terminating at a height of about one-half the vertical depth of the container. The width of the access door 48 may vary, up to an amount equal to the width of sidewall panel 32, and the cuts are usually positioned so that each is an equal distance from the vertical centerline of the sidewall panel. Preferably, the width of the door is not greater than about 80 percent of the corresponding dimension of the sidewall 32 so as to provide adequate vertical stacking strength at the four corners of the container. Score line 46 is a horizontal line of weakness extending between the lower ends and hingedly connects the access door 48 to the remainder of outer blank 30.

An inner reinforcing liner S is laminated to a major portion of the interior vertical sidewall surface of the outer blank 30. The length of the inner liner 50 is less than the interior horizontal perimeter of the outer blank 30, being scored to have a pair of sidewall panels 34' which flank a panel 32' and to have a pair of short end panels 52 hinged to the other ends of the panels 34', The end panels 52 are laminated to the inner surface of the sidewall panel 32 and extend past the cuts which define the access door 48. Thus, the access opening provided in the inner liner between the edges of the panels 52 is narrower than the access door 48, and these panels 52 provide lateral stops on each side of the access door which prevent it from being pushed inward beyond the vertical position. The lateral stops also provide a ready arrangement for securing the access door 48 in its closed position, as the lateral edge portions of the access door can be glued or stapled to the stop portions of the panels 52. The illustrated construction of the container 28 requires that only the outer blank 30 be cut, and facilitates the overall fabrication operation.

The containers herein described are most often used for shipment of farm products and the like of a type, such as melons, that must be manually loaded and/or unloaded and thereby require an access opening to facilitate efficient handling. Moreover, the large gross weights demand reinforcing in order to provide stacking strength and bulge resistance. Such a container is usually loaded at or near the field, and in some cases it will be mounted on a pallet to ease handling.

Once the container is manually loaded with the bulk product through the open access door, the door is secured in a closed position by gluing, stapling or the like. After securing the top closure, the containers are ready to be stacked and transported to the market.

Although the present invention has been discussed in terms of certain preferred embodiments, various modifications. such as would be obvious to those having the ordinary skill in the art. may be made without departing from the scope of the invention For example, instead of one access door located in the center of a sidewall panel, the door may be off-center or may be hinged along a vertical edge, or there may be more than one access door.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. A fiberboard container of generally rectangular parallepiped shape comprising a unitary outer blank of corrugated fiberboard and a separate and distinct inner liner of corrugated fiberboard which is laminated to at least a major portion of the inner vertical surface area thereof, vertical score means dividing said outer blank into four sidewall panels, said inner liner having a vertical height substantially equal to that of said sidewall panels and being laminated to all four sidewall panels at locations flanking said vertical score means to contribute substantially to the stacking strength of the container, means in at least one of said sidewall panels defining a generally rectangular access door therein located with a first horizontal edge of said access door being colinear with the upper edge of said panel and with a second edge of said door being the horizontal line along which said door is hinged to the remainder of said outer blank, and an access opening being provided in said inner liner of narrower horizontal dimensions than the horizontal dimensions of said access door so that a positive stop is provided by said inner liner at both vertical edges of said access door.

2. A container in accordance with claim I wherein said inner liner is laminated to substantially the entire inner vertical surface of said outer blank, with the portion of said inner liner where said access opening is formed being laminated to said access door.

3. A container in accordance with claim 1 wherein the length of said inner liner is significantly less than the horizontal perimeter of said container formed by said four sidewall panels and wherein said liner has two short end panels laminated to said one sidewall panel containing said access door, said short end panels being spaced apart a distance less than the horizontal dimen sion of said access door.

4. A container in accordance with claim 1 in which said second horizontal edge along which said access door is hinged to the container comprises at least two horizontal lines of weakness in said outer blank spaced apart to provide for easier opening of said access door.

5. A container in accordance with claim 4 wherein said inner liner covers substantially the entire interior vertical surface of said outer blank and said access door is laminated except for the lateral edge regions where said stops are provided. 

1. A fiberboard container of generally rectangular parallepiped shape comprising a unitary outer blank of corrugated fiberboard and a separate and distinct inner liner of corrugated fiberboard which is laminated to at least a maJor portion of the inner vertical surface area thereof, vertical score means dividing said outer blank into four sidewall panels, said inner liner having a vertical height substantially equal to that of said sidewall panels and being laminated to all four sidewall panels at locations flanking said vertical score means to contribute substantially to the stacking strength of the container, means in at least one of said sidewall panels defining a generally rectangular access door therein located with a first horizontal edge of said access door being colinear with the upper edge of said panel and with a second edge of said door being the horizontal line along which said door is hinged to the remainder of said outer blank, and an access opening being provided in said inner liner of narrower horizontal dimensions than the horizontal dimensions of said access door so that a positive stop is provided by said inner liner at both vertical edges of said access door.
 2. A container in accordance with claim 1 wherein said inner liner is laminated to substantially the entire inner vertical surface of said outer blank, with the portion of said inner liner where said access opening is formed being laminated to said access door.
 3. A container in accordance with claim 1 wherein the length of said inner liner is significantly less than the horizontal perimeter of said container formed by said four sidewall panels and wherein said liner has two short end panels laminated to said one sidewall panel containing said access door, said short end panels being spaced apart a distance less than the horizontal dimension of said access door.
 4. A container in accordance with claim 1 in which said second horizontal edge along which said access door is hinged to the container comprises at least two horizontal lines of weakness in said outer blank spaced apart to provide for easier opening of said access door.
 5. A container in accordance with claim 4 wherein said inner liner covers substantially the entire interior vertical surface of said outer blank and said access door is laminated except for the lateral edge regions where said stops are provided. 